The present invention relates to a case for a magnetic tape cassette and, in particular, to an improved case for a magnetic tape cassette which is used to keep a magnetic tape cassette for audio.
Conventionally, a magnetic tape cassette used for audio and the like (which will be hereinafter referred to simply as a tape cassette) includes a front opening portion into which a magnetic head or the like is inserted when the tape cassette is loaded into recording/reproducing apparatus or the like, and also a magnetic tape so mounted as to cross the front opening portion. Therefore, in order to prevent dust from getting into the tape cassette through front opening portion as well as to protect the magnetic tape exposed to the front opening portion and the whole tape cassette, the tape cassette is ordinarily stored in a case for a magnetic tape cassette (which will hereinafter be referred to simply as a storage case) for storage.
In FIG. 8, there is shown a conventional storage case. In this figure, a storage case 1 includes a cover part 11 and a casing part 12 which is connected to the cover part 11 openably and closably. And the cover part 11 includes a cover side opposing wall 13 to extend along one surface of a tape cassette 2 and a pocket 14 which is disposed in one end side of the cover side opposing wall 13 and into which the front opening portion 21 of the tape cassette 2 can be inserted. As shown in FIG. 1, in the storage case, an index card 3 and tape cassette 2 can be inserted into and removed from the pocket 4 along the cower side opposing wall 13.
On the other hand, the casing part 12 includes a casing side opposing wall 15 for covering the other surface of the tape cassette 2 loaded on the cover part 11, two pivotally mounting portions 16 for connecting the casing side opposing wall 15 to the cover part 11 rotatably, and a pair of rotation preventive projections 17 projectingly provided on the casing side opposing wall 15.
Here, the pivotally mounting portions 16 include, for example, two shaft-like projections provided in the inner portions of the casing part 12 to be fittable into two bearing holes respectively formed in the two side walls of the pocket 14 of the cover part 11, so that the cover part 11 and casing part 12 can be rotatably connected to each other. And, referring to the rotation preventive projections 17, when the cover part 11 or casing part 12 is rotated about the pivotally mounting portions 16 to close the casing side opposing wall 15 with respect to the cover part 11, the rotation preventive projections 17 are engaged with hubs 22 provided in the tape cassette 2 to prevent the tape from being loosened while it is kept.
In particular, each of the rotation preventive projections 17 includes a securing piece 18 the width dimension of which is set such that the securing piece 18 can be projected between mutually adjoining hub claws 23 provided on the inner periphery of each of the hubs 22, and a projection piece 19 provided perpendicularly to the securing piece 18 and having two side portions facing their opposing hub claws 23.
Both of the securing piece 18 and projection piece 19 are cut obliquely at the top end sides for easy fitting into the hub 22.
For reference, in FIG. 8, an arrow (a) indicates the direction of opening and closing of the cover part 11, while an arrow (b) indicates the direction of insertion of the index card and tape cassette 2 into the cover part 11.
Howewer, in the above conventional case, as shown in FIG. 9, the plate thickness dimension W1 of the securing piece 18 in the rotation preventive projection 17 is far smaller than a distance W0 between the two adjoining hub claws 23 of the hub 22. Due to this dimensional difference, even if the rotation preventive projection 17 is in engagement with the hub 22, the hub 22 is rotatable in the range of W2=W0-W1. Such rotational movement of the hub 22 causes the tape exposed to the front opening portion 21 to be loosened or causes the two side portions of the projection piece 19 to be shifted from their accurately determined opposing positions to the hub claws 23 to thereby fail to restrict the play of the hub. Therefore, when carrying the case, such free play causes unfavorable shocks to be given to the hub and tape.
Also, the position of the hub 22 of the tape cassette 2 is nearer to the rear end side of the cassette in the longitudinal direction of the cassette. That is, as shown in FIG. 10, when two tape cassettes 2 are superimposed on top of each other in a vertical direction (the other cassette is shown by imaginary lines), there actually exists a common area 4 in which the hub holes of the two tape cassettes are superimposed on each other, but, in fact, the position of the common area 4 is greatly shifted in the cassette longitudinal direction.
For this reason, in the storage case 1 in which the rotation preventive projections 17 are designed on the assumption that the tape cassette 2 is loaded into the pocket 14 from the front opening portion 21 side thereof, if the tape cassette 2 is inserted reversely in error, then the case cannot be closed and thus the direction of the tape cassette 2 must be corrected before it is loaded again.